Troubleshooting - Daikin APGM3 Service And Troubleshooting

TROUBLESHOOTING

TROUBLESHOOTING
Ignition Control Error Codes
The following presents probable causes of questionable
unit operation. Refer to Diagnostic Indicator Chart for
an interpretation of the signal and to this section for an
explanation.
Remove the control box access panel and note the number
of diagnostic LED flashes. Refer to Diagnostic Indicator
Chart for an interpretation of the signal and to this section
for an explanation.
Fault Recall (Two-Stage Models ONLY)
The ignition control is equipped with a momentary push-
button switch that can be used to display on the diagnostic
LED the last five faults detected by the control. The control
must be in Standby Mode (no thermostat inputs) to use the
feature. Depress the push-button switch for approximately
2 seconds. NOTE: Do not hold for longer than 4 seconds.
Holding the button for 4 seconds or higher will erase the
memory! Release the switch when the LED is turned
off. The diagnostic LED will then display the flash codes
associated with the last five detected faults. The order of
display is the most recent fault to the least recent fault.
Abnormal Operation - Heating
Internal Control Failure
If the integrated ignition control in this unit encounters an
internal fault, it will go into a "hard" lockout and turn off the
diagnostic LED. If diagnostic LED indicates an internal
fault, check power supply to unit for proper voltage, check
all fuses, circuit breakers and wiring. Disconnect electric
power for five seconds. If LED remains off after restoring
power, replace control.
External Lockout
An external lockout occurs if the integrated ignition control
determines that a measurable combustion cannot be
established within three (3) consecutive ignition attempts.
If flame is not established within the seven (7) second trial
for ignition, the gas valve is de-energized, 15 second inter-
purge cycle is completed, and ignition is reattempted. The
control will repeat this routine three times if a measurable
combustion is not established. The control will then shut off
the induced draft blower and go into a lockout state.
If flame is established but lost, the control will energize
the circulator blower at the heat speed and then begin a
new ignition sequence. If flame is established then lost on
subsequent attempts, the control will recycle for four (4)
consecutive ignition attempts (five attempts total) before
locking out.
The diagnostic fault code is 1 flash for a lockout due to
failed ignition attempts or flame dropouts. The integrated
control will automatically reset after one hour, or it can be
reset by removing the thermostat signal or disconnecting
the electrical power supply for over five seconds. If the
diagnostic LED indicates an external lockout, perform the
following checks:
• Check the supply and manifold pressures
• Check the gas orifices for debris
• Check gas valve for proper operation
• Check secondary limit
A dirty filter, excessive duct static, insufficient air flow, a
faulty limit, or a failed circulator blower can cause this limit
to open. Check filters, total external duct static, circulator
blower motor, blower motor speed tap (see wiring diagram),
and limit. An interruption in electrical power during a
heating cycle may also cause the auxiliary limit to open.
The automatic reset secondary limit is located on top of the
circulator blower assembly.
• Check rollout limit
If the burner flames are not properly drawn into the heat
exchanger, the flame rollout protection device will open.
Possible causes are restricted or blocked flue passages,
blocked or cracked heat exchanger, a failed induced draft
blower, or insufficient combustion air. The rollout protection
device is a manual reset limit located on the burner
bracket. The cause of the flame rollout must be determined
and corrected before resetting the limit.
• Check flame sensor
A drop in flame signal can be caused by nearly invisible
coating on the sensor. Remove the sensor and carefully
clean with steel wool.
• Check wiring
Check wiring for opens/shorts and miswiring.
IMPORTANT: If you have to frequently reset your gas/
electric package unit, it means that a problem exists that
should be corrected. Contact a qualified servicer for
further information.
Pressure Switch Stuck Open
A pressure switch stuck open can be caused by a faulty
pressure switch, faulty wiring, a disconnected or damaged
hose, a blocked or restricted flue, or a faulty induced draft
blower.
If the control senses an open pressure switch during the
pre-purge cycle, the induced draft blower only will be
energized. If the pressure switch opens after ignition has
begun the gas valve is de-energized, the circulator blower
heat off cycle begins, and the induced draft blower remains
on. The diagnostic fault code is two flashes.
Pressure Switch Stuck Closed
A stuck closed pressure switch can be caused by a faulty
pressure switch or faulty wiring. If the control encounters
a pressure switch stuck closed, the induced draft blower
remains off. The diagnostic LED code for this fault is three
(3) flashes.
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